“If you eat caviar every day it’s difficult to return to sausages.” –
Arsène Wenger, speaking in 1998.

At just before 4pm tomorrow, the distinctive figure of Arsene Wenger will take his place in the White Hart Lane dugout for what will be a record 40th north London derby.

Depending on how his increasingly erratic team performs in the 90 minutes that follow, Wenger’s body language will then oscillate between the professorial demeanour of his early Arsenal years to the angry, frustrated and even tortured expressions that have characterised more recent times.

Wenger has only actually lost five of those previous 39 derbies but he knows that his team’s ascendancy over Tottenham – and with it their cherished place among English football’s top four – has never been more seriously threatened. His once revered methods have also never faced more scrutiny. And, with his contract expiring next year, Wenger’s own position has never been the subject of more fervent debate. The sensitivity on that subject was evident in the now infamous press conference prior to the recent Bayern Munich match.

Wenger felt aggrieved that an inaccurate story had been published but his reaction also pointed towards a more deep-seated hurt at recent criticism. So, as he approaches a match that could define Arsenal’s season and conceivably even his future, is he really still relishing the challenge? Those with a detailed personal knowledge of Wenger’s working methods and current state of mind paint a consistent picture.

Wounded? Yes. But unwavering in his desire and belief? Absolutely. “Arsene is as focused and determined as he has ever been,” says Jacques Crevoisier, a friend of 40 years, who provides psychological profiles of Arsenal’s young players. “He is a big fighter and one of the greatest warriors I ever met in football in the most difficult situations. He is the first leader and able to cope with such pressure.”

Those familiar with Wenger’s working patterns say that, away from the cameras, nothing has changed in almost 17 years at the club. He is generally still the first to arrive at Arsenal’s London Colney training base and the last to leave. At 63, he continues to follow the same diet as the players and the highlight of his day remains the hour or so he spends, stopwatch in hand and whistle in mouth, overseeing training. Stories of him watching ludicrous amounts of matches from around the world continue.

“I consider myself a football nut but he lives, eats and sleeps it,” says Bob Wilson, his former goalkeeping coach. “That has never ever changed. There is absolutely no change when we talk. If I throw up any topic, his enthusiasm and his interpretation on something still always makes me think. He is a one-off – totally different. He is an academic who is in love with football.

“He has total belief in himself and he feels this responsibility to the people who have paid to go to matches. He believes that win, lose or draw, the person going away should say that it was an amazing game to watch.”

There is no disguising the current hurt, however. Wenger was named ‘sport’s sorest loser’ in one magazine poll in 2008 and the added practice of the past five years appears to have taken a physical toll.

He seems to look just a little slimmer, greyer and more stressed every season. “He wants to win more than anyone I have ever met in football,” says Damien Comolli, Arsenal’s former scout. “In the third season at Nancy, he lost the last match before the mid-winter break. He shut himself away on his own for the fortnight, and didn’t even have his family around for Christmas. He’d make himself physically ill after a defeat.”

Wilson believes that defeats – and there have already been 10 this season - do visibly age Wenger. “Agony is the only word I can use to describe it,” he says. “He cares so much and has such a love for the club. He talks about it like a marriage. He believes that Arsenal has been his destiny. When I see his face, if we have won, there is a relaxation in every muscle. I see that same face after we have lost or not played particularly well and it is a man 10 years older.”

Among friends of Wenger, there is a shared frustration that Arsenal’s recent decline is generally measured in the narrow context of his extraordinary past success. After all, if you go back before Wenger arrived, Arsenal had achieved just 23 top four finishes in 92 seasons.

They are now going for their 17th in a row under his management. David Dein, when speaking last month on Sky Sports’ Footballers’ Football Show, put it like this: “It is very simple, under Arsene Wenger’s stewardship, Arsenal have had good times and very good times. He is the most driven and focused person I have ever met in football.”

Comolli can still recall the day that Roman Abramovich arrived at Chelsea in 2003 and Wenger predicted a profound alteration of what he called “the scenery”. Add in Manchester City, as well as the constraints of paying for a new stadium, and an eight year trophy drought becomes more understandable if no easier to accept.

“The issue is not Arsene, but simply the fact that they have been fighting against teams with more money and with enormous debts,” says Crevoisier. “If the Financial Fair Play is implemented, the most healthy club in Europe is Bayern Munich and the second is Arsenal.”

The question of what happens beyond next season now lingers. A potentially momentous decision awaits over the next year. Wenger’s friends all suggest that nothing has been decided beyond his contract in 2014 and that it will be the last thing on his mind just now.

“He is intelligent enough to know when enough’s enough if people really wanted him to go,” says Wilson. “There will come a time but I really don’t think it is that time yet. We want it to finish in the way it should finish: under his terms and with a bit of silverware to show that his belief in the way the game should be played works.”

Health will also be a huge factor. Wenger has previously told friend that he would look carefully at his position when he was into his 60s and has admitted to concern at the untold damage he might be doing to himself. Against that, football has been an obsession since he was old enough to listen to the stories of players from his local village team in Duttlenheim, where his parents ran La Croix D’Or pub.

“I don’t think he could live without it,” says Wilson. “I expect Arsene to still be a manager, here or somewhere else, at Alex Ferguson’s age.

Football can give him incredible pain when things don’t go right but seeing people perform just gives him so much joy.” And could he really go elsewhere? For all the recent difficulties at Arsenal, his standing in Europe remains considerable. “In his recent press conference,

Arsene said, ‘one day I will tell you all the offers I have had’ but we know them,” says Crevoisier. “It is France. It is England. It is Real Madrid. It is Bayern Munich. It is Inter Milan. It is Barcelona. They were all desperate to get him. He never accepted to talk to them and it is something people should never forget.

“At the end of the season, Jose Mourinho will leave Real Madrid. If Madrid feel that Arsene is not happy, Arsene will be the first choice. I don’t say he will go there but it as simple as that.

“His reputation across Europe is as one of the top six coaches in the world. Some fans say, ‘maybe it is the time for Arsene to leave’ but he would find himself immediately in a big club and the question is who will come in to replace him at Arsenal?

“I think he will respect his contract until 2014. Then, if he feels people don’t like him, maybe he will not extend his contract. He sets the highest standards of himself and I don’t think he would stay if he did not feel people were satisfied with him.”

Wenger has himself described his future as “short-term” but, if results do turn back in Arsenal’s favour, the most telling insight can perhaps be found in an interview he gave back in 2011. “The time goes by at the speed of light,” he said. “All of these years haven’t at all changed the fact that I’m always looking ahead to the next match, hoping it will be a perfect match but knowing it won’t be. I remain addicted to the next match, like a drug.”

That search for perfection could yet extend at Arsenal into a third decade.